User's Comments:

Letsee...he'll likely betray our heroine and sic his minions on her after she hands over the ribbon, whereupon Natsumi will snap out of it and turn on him, destroying his puppet body and reversing the curse. But this story has thrown a few twists here and there, so we'll see...

One twist would be for him to KEEP his end of the bargain, whereupon the twin goddesses appear and chastise Megumi, one of the two pointing out that an avatar of Desire wouldn't have given in so easily. Then our former villain is given back her ribbon and has to play the role of the heroine...

Incidentally, Desire, or Tanha, is one of the three poisons, or causes of suffering, in the Buddhist religion. I find it odd that the goddess of Desire in Playtime is portrayed more or less as a force of good in the story given the setting.

Another possibility: Dolly removing the ribbon is, in fact, an illusion. She's still wearing the ribbon but used her powers to create a dummy/double/image. She's expecting him to betray her and just wants him to drop the shield.

Can see what will happen
I can see what's going to happen a thousand miles away. The ribbon will turn on the lord of nightmares the moment he touches it (assuming it's not a decoy as someone else pointed out). Victory. Next!

@Alex Warlorn: The mask character was far more malevolent in the original comic book than the movie - more of an antihero - and the mask from the movie wasn't exactly a nice guy either - chaotic neutral with a selfish mindset. Dolly is just as mischievous, but her pranks are far, far less harmful and she goes out of her way to do good.